ADH, also known as vasopressin (AVP), is a small peptide composed of nine amino acid residues, also known as arginine pressor. ADH is a peptide hormone consisting of 9 amino acids, which is synthesized in the supraoptic and paraventricular nuclei of the hypothalamus and transported through the hypothalamic-pituitary bundle to the pituitary neural lobe (posterior lobe) for storage, hence the name posterior pituitary hormone. ADH is secreted into the blood when needed and transported through the blood to target organs for action, mainly in the kidney and liver. ADH is secreted into the blood and acts on V2 receptors in the basal cell membranes of the collecting ducts and distal tubules of the kidney, causing the activation of adenylate cyclase, which increases cyclic adenosine monophosphate in the epithelial cells and phosphorylates aquaporin 2 (AQP2) in the cell membranes, increasing the permeability of the luminal membranes and opening the “water channels”, resulting in increased water reabsorption and urine This leads to increased water reabsorption and concentration of urine, resulting in a significant antidiuretic effect. What is the cause of increased secretion of antidiuretic hormone (ADH)? The increased secretion of antidiuretic hormone (ADH) is not regulated by plasma osmolality, resulting in a series of clinical manifestations such as water retention, increased urinary sodium excretion, and dilutional hyponatremia. In addition to severe craniocerebral injury, cervical medullary injury, severe intracranial infection and acute stage of cerebrovascular disease (10%~14%), there are malignant tumors and lung tumors, etc.